JP2009192374A - Contact probe, electronic circuit testing device using it, and manufacturing method of contact probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact probe capable of cleaning a plunger simply and inexpensively. <P>SOLUTION: This contact probe is equipped with a cylindrical sleeve 22; the plunger 24 sliding in the axial direction inside the sleeve 22; a coil spring 26 stored inside the sleeve 22, and axially urging the plunger 24 of the sleeve 22; and a short pin 28 in contact with a fixed end 26a of the coil spring 26. The sleeve 22 is provided with a caulking part 22a for preventing fallout of the coil spring 26, and the plunger 24 is constituted detachably without interference with the caulking part 22a. Since the plunger 24 can be dismounted simply from the sleeve 22, after the plunger 24 is dismounted from the sleeve 22, the whole plunger can be cleaned only by being dipped into a plating bath. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a contact probe, and more particularly to a movable contact probe having a spring property. The present invention also relates to a test apparatus for an electronic circuit such as a semiconductor integrated circuit using such a contact probe. Furthermore, the present invention relates to a method for manufacturing such a contact probe.

  The manufacturing process of a semiconductor integrated circuit is classified into a diffusion process (pre-process) for forming various electronic circuits on a silicon wafer and an assembly process (post-process) for packaging individual chips. These pre-process and post-process In either case, an operation test is performed to confirm whether each chip operates correctly. Among these, an electronic circuit test apparatus (tester) using a movable contact probe having a spring property is often used for an operation test performed in a later process. In addition, movable contact probes are also widely used for evaluating characteristics of printed circuit boards and various electronic circuits. As this type of contact probe, a contact probe called “pogo pin” is generally used (see Patent Documents 1 to 7).

  FIG. 5 is a schematic cross-sectional view showing the structure of a general pogo pin.

  The pogo pin 10 shown in FIG. 5 includes a cylindrical sleeve 12, a plunger 14 that slides in the sleeve 12 in the axial direction, a coil spring 16 that biases the plunger 14, and a fixed end 16 a of the coil spring 16. It is comprised by the short pin 18 arrange | positioned at the side. As materials for these members, conductive materials such as metals are used.

  The plunger 14 includes a sliding portion 14 a that contacts the inner wall of the sleeve 12 and has a tip protruding from the sleeve 12, a spring receiving portion 14 b that contacts the movable end 16 b of the coil spring 16, and the sliding portion 14 a and the spring receiving portion 14 b. It is comprised by the connection part 14c to connect. The tip 14x of the sliding portion 14a is a portion that comes into contact with an electrode (DUT electrode) of a subject (DUT: Device Under Test) (not shown). On the other hand, the short pin 18 is a portion in contact with an electrode of a tester (not shown).

  The sleeve 12 is provided with a crimped portion 12a that is crimped into a ring shape, and the inner diameter of the sleeve 12 is narrowed at this portion. More specifically, the inner diameter of the portion where the crimping portion 12a is provided is narrower than the outer diameter of the sliding portion 14a of the plunger 14 and the spring receiving portion 14b. The outer diameter of the connecting portion 14c is set to be smaller than the inner diameter of the portion where the crimping portion 12a is provided so as not to interfere with the crimping portion 12a.

  With this configuration, when the plunger 14 is stroked in a direction in which the coil spring 16 is contracted, the sliding portion 14a of the plunger 14 interferes with the crimping portion 12a, and further strokes are prevented. Thereby, the damage by the coil spring 16 being compressed to the contact length is prevented. On the other hand, when the plunger 14 is stroked in the direction in which the coil spring 16 is extended, the spring receiving portion 14b of the plunger 14 interferes with the crimping portion 12a, and further strokes are prevented. This prevents the coil spring 16 and the short pin 18 from falling off the sleeve 12.

  As described above, the tip 14x of the plunger 14 is a portion that contacts the DUT electrode. Since the DUT electrode is often attached with a thin metal oxide film or organic dirt, when the operation test is repeatedly performed, the dirt is also attached to the tip 14x of the plunger 14. Furthermore, the metal constituting the DUT electrode may diffuse to the plunger 14 side to form a high resistance alloy. When such dirt adhesion or alloy formation occurs, the contact resistance between the contact probe and the DUT electrode increases or the resistance value varies, which hinders a normal operation test. For this reason, it is necessary to clean the contact probe every time the operation test is performed a predetermined number of times.

  Examples of contact probe cleaning methods include a method of removing dirt using a chemical solution, a method of removing dirt using abrasive paper or a wire brush, and a method of re-plating. However, the method of removing dirt using a chemical solution is effective against organic dirt, but cannot remove a metal oxide film or an alloy. Further, the method of removing dirt using abrasive paper or a wire brush is also effective for metal oxide films and alloys, but since the plunger 14 is worn, the life of the contact probe is shortened.

On the other hand, the re-plating method is effective against all kinds of dirt, and does not cause the wear of the plunger 14, so it is considered to be the most desirable cleaning method.
JP-A-5-55315 Japanese Patent Laid-Open No. 10-189087 Japanese Patent Laid-Open No. 11-174084 Japanese Patent Laid-Open No. 11-176548 JP 2002-22768 A JP 2004-85260 A JP 2005-351785 A

  However, since the contact probe itself becomes unusable when the plating solution enters the inside of the sleeve 12, only the tip 14x of the plunger 14 needs to be accurately immersed in the plating bath in the re-plating process. For this reason, the replating process requires a very careful operation using a dedicated maintenance jig, and it has been difficult to easily and inexpensively clean a large number of contact probes.

  Accordingly, an object of the present invention is to provide a contact probe capable of easily and inexpensively maintaining a plunger and an electronic circuit test apparatus using the contact probe. It is another object of the present invention to provide a method for manufacturing such a contact probe.

  A contact probe according to the present invention includes a cylindrical sleeve, a plunger that slides in the sleeve in the axial direction, and a biasing means that is accommodated in the sleeve and biases the plunger in the axial direction of the sleeve. The sleeve has a drop-off preventing portion that prevents the urging means from dropping off, and the plunger is configured to be detachable without interfering with the drop-off preventing portion.

  According to the present invention, since the plunger is configured to be detachable, the plunger can be easily detached from the sleeve. For this reason, after removing the plunger from the sleeve, it becomes possible to perform cleaning only by immersing the whole plunger in the plating bath.

  In the present invention, it is preferable that the drop-off preventing portion is a crimped portion in which a part of the sleeve is deformed inward, and a portion of the sleeve having the same position in the axial direction as the crimped portion constitutes a non-crimped portion. . According to this, since the inner diameter of the sleeve is not entirely reduced in the portion where the caulking portion is formed, but is only partially reduced, the diameter of the contact surface with respect to the biasing means of the plunger is sufficiently increased. Can be secured. Thus, the biasing means can be reliably pressed by the plunger having a shape that does not interfere with the crimping portion.

  In the present invention, it is preferable that the plunger has a sliding portion that contacts the inner wall of the sleeve and a protruding portion that protrudes from the sleeve, and the sliding portion of the plunger is provided with a guide surface that contacts the crimping portion. . According to this, since the plunger slides along the guide surface, the plunger can be slid without causing rattling or the like. If the guide surface is spiral, the plunger slides while rotating around the axis. For this reason, when the stroke is made in a state where the tip of the plunger is in contact with the DUT electrode, the DUT electrode and the tip of the plunger are wiped (rubbed). By this rotating operation, the metal oxide film and the organic film adhering to the DUT electrode are destroyed, and it becomes possible to ensure a good contact.

  It is preferable that the plunger further includes a stopper portion that is provided on the side opposite to the protruding portion as viewed from the sliding portion and limits the amount of contraction of the urging means. According to this, it becomes possible to prevent the urging means from being damaged due to excessive contraction. In addition, since the stroke amount of the plunger is limited by the stopper portion, it is possible to reliably prevent interference between the plunger and the caulking portion. Furthermore, when the operation of inserting the plunger into the sleeve is performed, since the stopper portion serves as a guide, the insertion operation can be easily performed.

  In the present invention, the biasing means is preferably a coil spring (spiral spring), and the stopper portion is preferably inserted into the inner diameter portion of the coil spring. According to this, it becomes possible to restrict | limit the stroke amount of a plunger reliably, preventing interference with a coil spring and a stopper part.

  In the present invention, the diameter of the protruding portion of the plunger is preferably smaller than the diameter of the sliding portion of the plunger. According to this, since a step is formed at the boundary portion between the sliding portion and the projecting portion, it is possible to prevent the plunger from falling off during actual use using this step.

  An electronic circuit test apparatus according to the present invention includes a plunger having the above contact probe, a probe holder that accommodates the contact probe so that the protruding portion of the plunger is exposed, and a through hole that penetrates the protruding portion of the plunger. And a stopper, and the diameter of the through hole provided in the plunger stopper is smaller than the diameter of the sliding portion of the plunger. According to the present invention, in actual use, it is possible to prevent the plunger from dropping off by the plunger stopper. On the other hand, during maintenance, the plunger can be easily removed from the sleeve by removing the plunger stopper.

  The method of manufacturing a contact probe according to the present invention includes a step of inserting a caulking assembly jig having a caulking stopper surface into the sleeve after inserting at least an urging means into the cylindrical sleeve, and a sleeve toward the caulking stopper surface. The caulking process is performed from one direction to prevent the urging means from falling off the sleeve, and after the caulking part is formed, a plunger provided with a guide surface in contact with the caulking part is inserted. And a step of performing. According to the present invention, since the plunger is inserted after the crimped portion is formed on the sleeve, the contact probe can be manufactured very efficiently.

  As described above, according to the present invention, it is possible to provide a contact probe capable of easily and inexpensively maintaining a plunger and an electronic circuit test apparatus using the contact probe. Further, according to the present invention, it is possible to manufacture the contact probe very efficiently.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic cross-sectional view showing the structure of a contact probe according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the contact probe 20 according to the present embodiment includes a cylindrical sleeve 22, a plunger 24 that slides in the sleeve 22 in the axial direction, and a plunger 24 that is accommodated in the sleeve 22. Is formed by a spiral coil spring 26 that urges the sleeve 22 in the axial direction of the sleeve 22 and a short pin 28 that contacts the fixed end 26 a of the coil spring 26. Of these members, at least the sleeve 22, the plunger 24, and the short pin 28 are all made of a conductive material such as metal. The material of the coil spring 26 is not particularly limited, but it is preferable to use a conductive material such as metal.

  The plunger 24 includes a sliding portion 24a that contacts the inner wall of the sleeve 22, a protruding portion 24b that protrudes from the sleeve 22, and a stopper portion 24c that is provided on the opposite side of the protruding portion 24b as viewed from the sliding portion 24a. ing. The tip 24x of the projecting portion 24b is a portion that contacts an electrode (DUT electrode) of a subject (not shown). On the other hand, the short pin 28 is a portion in contact with an electrode of a tester (not shown). As shown in FIG. 1, the diameters of the protruding portion 24b and the stopper portion 24c are both smaller than the diameter of the sliding portion 24a. Therefore, a step 32 is formed at the boundary portion between the sliding portion 24a and the protruding portion 24b, and a step 34 is formed at the boundary portion between the sliding portion 24a and the stopper portion 24c. The stopper portion 24 c is inserted into the inner diameter portion of the coil spring 26, and the step 34 is in contact with the movable end 26 b of the coil spring 26.

  On the other hand, the sleeve 22 is provided with a crimped portion 22a that is crimped, and the inner diameter of the sleeve 22 is narrow at this portion. In the present embodiment, the caulking portion 22a has a non-ring shape, and has a linear shape that is caulked from only one direction. That is, a portion of the sleeve 22 having the same position in the axial direction as the caulking portion 22a constitutes a non-caulking portion 22b.

  The caulking portion 22a has a function as a drop-off prevention portion that prevents the coil spring 26 and the short pin 28 from dropping off. As shown in FIG. 1, a guide surface 40 that is in contact with the crimping portion 22 a is provided on the sliding portion 24 a of the plunger 24. For this reason, when the plunger 24 is stroked, the stroke is made while the guide surface 40 and the caulking portion 22a are in contact with each other. The sliding portion 24a of the plunger 24 has a non-guide surface 42 whose axial position is the same as that of the guide surface 40, and when the plunger 24 is stroked, the non-guide surface 42 and the non-caulking portion. Stroke is made while contacting 22b.

  2A and 2B are diagrams for explaining the structure of the plunger 24 in more detail. FIG. 2A is a schematic plan view, FIG. 2B is a schematic side view, and FIG. 2C is a CC line shown in FIG. (D) is a schematic cross-sectional view along the line DD shown in (b), and (e) is a schematic cross-sectional view along the line EE shown in (b).

  As shown in FIG. 2, in this embodiment, the guide surface 40 of the plunger 24 is helical. For this reason, when the plunger 24 is stroked, the plunger 24 rotates around the axis by the guide of the caulking portion 22a. For this reason, if the stroke is made in a state where the tip 24x of the plunger 24 is in contact with the DUT electrode, the DUT electrode and the tip 24x of the plunger 24 perform wiping (rubbing). By this rotation operation, the metal oxide film and the organic film to which the DUT electrode is attached are destroyed, and it is possible to ensure a good contact.

  In the contact probe 20 according to the present embodiment, the step 34 formed at the boundary portion between the sliding portion 24a and the stopper portion 24c functions as a spring receiving portion. For this reason, when the plunger 24 is stroked in a direction in which the coil spring 26 is contracted to some extent, the movable end 26b of the coil spring 26 is initially in contact with the step 34 of the plunger 24, but is extended by a certain amount. As a result, the movable end 26 b of the coil spring 26 interferes with the caulking portion 22 a and separates from the plunger 24. When the stroke is further increased, the plunger 24 is released from the urging force of the coil spring 26 and is extracted from the sleeve 22 as it is without interfering with the caulking portion 22a.

  On the contrary, when the plunger 24 is inserted into the sleeve 22, the movable end 26b of the coil spring 26 is initially in contact with the crimping portion 22a, but when the plunger 24 is inserted by a certain amount, the movable end 26b of the coil spring 26 is It contacts with the step 34 of the plunger 24 and is separated from the caulking portion 22a. As a result, the urging force of the coil spring 26 is applied to the plunger 24. If the plunger 24 is stroked in the direction in which the coil spring 26 is contracted in this state, the stopper portion 24c of the plunger 24 interferes with the short pin 28, and further stroke is prevented. In addition, since the diameter of the stopper part 24c is smaller than the diameter of the sliding part 24a, the operation | work which inserts the extracted plunger 24 in the sleeve 22 can be performed easily.

  As described above, in the contact probe 20 according to the present embodiment, unlike the conventional contact probe 10 shown in FIG. 5, the crimping portion 22 a is provided ahead of the step 34 of the plunger 24 (on the coil spring 26 side). The spring receiving part larger than the internal diameter of the provided part is not provided. That is, the sliding portion 24a itself is in contact with the crimping portion 22a, and the step 34 formed at the boundary portion between the sliding portion 24a and the stopper portion 24c functions as a spring receiving portion. As a result, the plunger 24 can be extracted from the sleeve 22 without interfering with the crimping portion 22a.

  In addition, since the shape of the crimping portion 22a is a non-ring shape and has a linear shape that has been crimped only from one direction, the inner diameter of the sleeve 22 is not generally reduced in this portion. It ’s only partly thin. For this reason, even if it is the plunger 24 which can be attached or detached without interfering with the crimping part 22a, the diameter of the part used as a spring receiving part can fully be ensured, and the coil spring 16 can be pressed correctly. Become.

  As described above, in the contact probe 20 according to the present embodiment, since the plunger 24 is detachable, the plunger 24 is removed from the sleeve 22 and then cleaned by simply immersing the whole plunger 24 in a plating bath. It becomes possible. Further, even if the plunger 24 is damaged due to an operator's mistake or a tester's malfunction, it is not necessary to replace the entire contact probe 20, and only the damaged plunger 24 can be easily replaced. It becomes possible.

  In addition, when the coil spring 26 is contracted by a certain amount, the short pin 28 positioned with respect to the sleeve 22 and the stopper portion 24c come into contact with each other, thereby preventing the coil spring 26 from being damaged due to excessive contraction. Further, since the stroke amount of the plunger 24 is limited by the stopper portion 24c, it is possible to reliably prevent interference between the plunger 24 and the caulking portion 22a.

  In particular, in the contact probe 20 according to the present embodiment, the crimped portion 22a is non-ring-shaped and has a shape that is crimped only from one direction, so that the crimped portion is compared to a ring-shaped configuration. The strength of the sleeve 22 at this portion is low. For this reason, if the stopper portion 24c is deleted, it is necessary to set the length of the sleeve 22 and the plunger 24 to a sufficient length in order to prevent damage due to the caulking portion 22a biting into the plunger 24. Arise. On the other hand, if the stopper part 24c is provided, before the caulking part 22a bites into the plunger 24, further strokes are limited. Therefore, the length of the sleeve 22 and the plunger 24 should be set short. Can do. As a result, the high frequency characteristics of the contact probe 20 can be improved.

  In the contact probe 20 according to the present embodiment, a notch 28 a is provided at the tip of the short pin 28. As a result, the tip of the short pin 28 is in contact with the land on the tester side with the tip of the short pin 28 being offset from the center line of the plunger 24 that strokes. For this reason, when the plunger 24 is stroked, a rotational moment is applied to the entire contact probe 20, and the inner wall of the sleeve 22 and the sliding portion 24a of the plunger 24 slide in a pressed state. Thereby, it is possible to reliably prevent the generation of noise due to temporary contact failure between the sleeve 22 and the plunger 24. Further, the contact between the short pin 28 and the sleeve 22 is ensured.

  FIG. 3 is a schematic cross-sectional view for explaining the method for manufacturing the contact probe 20 according to the present embodiment.

  In manufacturing the contact probe 20 according to the present embodiment, the sleeve 22 is first prepared, and the short pin 28 and the coil spring 26 are inserted into the sleeve 22 in this order. Next, the caulking assembly jig 50 having the caulking stopper surface 50 a is inserted into the sleeve 22, and in this state, the sleeve 22 is caulked by the caulking punch 52. The caulking process is performed from one direction toward the caulking stopper surface 50a. As a result, a crimping portion 22a is formed on the sleeve 22, and the coil spring 26 and the short pin 28 are prevented from falling off. The distance between the caulking stopper surface 50a and the inner wall of the sleeve 22 is substantially the same as the distance between the guide surface 40 of the plunger 24 and the inner wall of the sleeve 22, so that the caulking amount can be accurately controlled. Become.

  Then, after the caulking assembly jig 50 is removed, the plunger 24 is inserted into the sleeve 22 to complete the contact probe 20 according to the present embodiment. As described above, the contact probe 20 according to the present embodiment can insert the plunger 24 after forming the crimping portion 22a. On the other hand, when the caulking portion 22a is formed after the plunger 24 is inserted, the caulking punch 52 needs to be pressed against the guide surface 40 of the plunger 24, and the position control of the plunger 24 is essential. . In the present embodiment, such position control is unnecessary, and the contact probe 20 can be manufactured very efficiently.

  FIG. 4 is a schematic cross-sectional view showing the structure of the main part of an electronic circuit test apparatus using the contact probe 20.

  The electronic circuit test apparatus 100 shown in FIG. 4 includes a probe holder 110 that holds the contact probe 20, a plunger stopper 120, and a printed wiring board 130. The probe holder 110 is a member that is supported by accommodating the contact probe 20 so that the protruding portion 24 b of the plunger 24 is exposed. The plunger stopper 120 is fixed to one surface 111 and printed on the other surface 112. The wiring board 130 is fixed.

  The plunger stopper 120 has a through hole 121, and the protruding portion 24 b of the plunger 24 passes through the through hole 121. The diameter of the through-hole 121 is smaller than the diameter of the sliding portion 24a of the plunger 24. For this reason, the stepped portion 32 of the plunger 24 and the plunger stopper 120 interfere with each other, thereby preventing the plunger 24 from falling off. Yes. The printed wiring board 130 is formed with a probe connection land 131 in contact with the short pin 28. The probe connection land 131 is connected to a test circuit (not shown).

  In FIG. 4, only one contact probe 20 is shown. However, in the actual electronic circuit testing apparatus 100, the same number of contact probes 20 as the number of DUT electrodes are used.

  With such a configuration, during actual use, it is possible to correctly perform an operation test while preventing the detachable plunger 24 from falling off. On the other hand, when cleaning the plunger 24, the plunger stopper 120 is used. By removing from the probe holder 110, the plunger 24 can be easily extracted.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above embodiment, the sleeve 22 is cylindrical. However, the present invention is not limited to this, and any shape may be used as long as it is cylindrical. However, as in the above embodiment, in order to make the plunger 24 stroke while rotating around the axis, it is desirable that the sleeve 22 is cylindrical.

  In the above embodiment, the coil spring (spiral spring) 26 is used as means for biasing the plunger 24 in the axial direction of the sleeve 22, but the present invention is not limited to this. Therefore, a non-spiral spring may be used, or an urging means other than the spring may be used. However, when the stopper 24c is provided on the plunger 24 as in the above embodiment, it is desirable to use the coil spring 26 as the biasing means.

  In the above embodiment, the coil spring 26 is prevented from falling off by providing the crimping portion 22a on the sleeve 22. However, the present invention is not limited to this, and the biasing means such as the coil spring is dropped off. Any means may be used as long as it can prevent the interference and does not interfere with the plunger.

  In the above-described embodiment, the guide surface 40 provided on the plunger 24 is formed in a spiral shape so that the plunger 24 can slide while rotating around the axis. It is not limited. Therefore, the plunger may stroke linearly.

  Moreover, in the said embodiment, although the stopper part 24c is provided in the plunger 24, providing this in this invention is not essential. However, if the stopper 24c is provided on the plunger 24, the stroke amount of the plunger is limited, so that the coil spring and the caulking portion are prevented from being damaged, and the work of inserting the extracted plunger into the sleeve is easy. It is particularly preferable to provide a stopper portion on the plunger.

  Moreover, in the said embodiment, although the diameter of the protrusion part 24b of the plunger 24 is smaller than the diameter of the sliding part 24a, both diameters may be the same. If both diameters are the same, the plunger stopper 120 shown in FIG. 4 cannot be used. However, if the tester is a type of tester that always uses the plunger facing upward, it is actually used due to the action of gravity. It is possible to prevent the plunger from dropping off at the time.

  In the above embodiment, the contact probe 20 is provided with the short pin 28. However, in the present invention, the short pin 28 is not essential, and the fixed end 26a of the coil spring 26 is in contact with the sleeve 22 itself. It doesn't matter. Further, even when the short pin 28 is provided, it is not essential to provide the offset notch 28a at the tip thereof.

  The contact probe according to the present invention can be used not only for an operation test of a semiconductor integrated circuit in a later process, but also for evaluation and inspection of electrical characteristics of various electronic circuits such as an electronic component and a printed wiring board.

It is a schematic sectional drawing which shows the structure of the contact probe by preferable embodiment of this invention. It is a figure for demonstrating in detail the structure of the plunger 24, (a) is a schematic plan view, (b) is a schematic side view, (c) is a schematic diagram along the CC line shown in (b). Sectional drawing, (d) is a schematic sectional view along the line DD shown in (b), and (e) is a schematic sectional view along the line EE shown in (b). It is a schematic sectional drawing for demonstrating the manufacturing method of the contact probe by preferable embodiment of this invention. It is a schematic sectional drawing which shows the structure of the principal part of the electronic circuit testing apparatus by preferable embodiment of this invention. It is a schematic sectional drawing which shows the structure of a general pogo pin.

Explanation of symbols

20 Contact probe 22 Sleeve 22a Caulking portion 24 Plunger 24a Sliding portion 24b Protruding portion 24c Stopper portion 24x Tip 26 Coil spring 26a Fixed end 26b Movable end 28 Short pin 28a Notch 32, 34 Step 40 Guide surface 50 Caulking assembly jig 50a Caulking stopper surface 52 Caulking punch 100 Electronic circuit testing device 110 Probe holder 111 One surface 111 of the probe holder 111 Other surface of the probe holder 120 Plunger stopper 121 Through hole 130 Printed wiring board 131 Probe connection land

Claims (9)

A cylindrical sleeve, a plunger that slides in the axial direction in the sleeve, and a biasing means that is accommodated in the sleeve and biases the plunger in the axial direction of the sleeve,
The contact probe according to claim 1, wherein the sleeve has a drop-off preventing portion that prevents the urging means from dropping off, and the plunger is detachable without interfering with the drop-off preventing portion.   2. The contact probe according to claim 1, wherein the drop-off prevention portion includes a caulking portion in which a part of the sleeve is deformed inward. The plunger has a sliding portion in contact with the inner wall of the sleeve, and a protruding portion protruding from the sleeve,
The contact probe according to claim 2, wherein the sliding portion of the plunger is provided with a guide surface in contact with the caulking portion.   The contact probe according to claim 3, wherein the guide surface is spiral, and the plunger slides while rotating around an axis.   5. The plunger according to claim 3, further comprising a stopper portion that is provided on a side opposite to the projecting portion when viewed from the sliding portion and limits a contraction amount of the urging means. Contact probe according to.   The contact probe according to claim 5, wherein the biasing means is a coil spring, and the stopper portion is inserted into an inner diameter portion of the coil spring.   The contact probe according to claim 3, wherein a diameter of the protruding portion of the plunger is smaller than a diameter of the sliding portion of the plunger. The contact probe according to claim 7, a probe holder that accommodates the contact probe so that the protruding portion of the plunger is exposed, and a plunger stopper having a through hole that penetrates the protruding portion of the plunger. ,
The diameter of the said through-hole provided in the said plunger stopper is smaller than the diameter of the said sliding part of the said plunger, The electronic circuit test apparatus characterized by the above-mentioned. A step of inserting a caulking assembly jig having a caulking stopper surface into the sleeve after inserting at least the urging means into the cylindrical sleeve;
Forming a caulking portion that prevents the urging means from falling off the sleeve by caulking the sleeve from one direction toward the caulking stopper surface;
And a step of inserting a plunger provided with a guide surface in contact with the caulking portion after forming the caulking portion.

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